Dynamic Support for Distributed Certification Authority in Mobile Ad Hoc Networks

Use of public key cryptography and certificates is one of the effective ways of securing a mobile ad hoc network (MANET). Certificates are issued by certification authority (CA). In order to use a CA in MANETs, researchers have proposed the design of a distributed CA based on threshold cryptography. In such schemes, the functionality of CA is distributed amongst nodes in the network. With a distributed CA, certification service is provided by a coalition of threshold number of nodes. In the design of a distributed CA that we follow, a node obtains the certification service by communicating with its one-hop neighbors. With such distributed CA, when the number of neighbors of a node, also called node degree, reduces, there is a substantial increase in the certification service delays. In this paper we propose a solution for the above problem using a suite of network monitoring protocols. The proposed protocol suite is based on the observation that when the node degree varies, the delays involved in obtaining certificates may be reduced by dynamically varying the threshold value. The proposed protocols dynamically adjust the threshold value by monitoring the average node degree of the network and thereby prevent an increase in certification service delay